This application incorporates by reference Taiwan application Serial No. 090128874, filed Nov. 21, 2001.
1. Field of the Invention
The invention relates in general to a plasma display panel (PDP), and in particular, to a PDP with low firing voltage.
2. Description of the Related Art
The plasma display panel (PDP) has a great potential in the big-size flat display panel market. A conventional PDP usually requires a high firing voltage to transform an ionized gas into plasma. Driving the PDP at high voltage not only requires expensive driving and control components, but may also damages the components thus shortening their life spans.
FIG. 1 illustrates a cross-sectional view of the PDP 100 according to a conventional method. The PDP 100 includes a front substrate 102 and a rear substrate 104. The spacing between the front substrate 102 and the rear substrate 104 is filled with a mixture of inert gases. The rear substrate 102 has a plurality of sustain electrodes 108 and scan electrodes 110, which are arranged alternately and in parallel thereon. The front substrate 104 has an address electrode 106, which is orthogonal to the sustain electrode 108 and the scan electrode 110. Moreover, a dielectric layer 114 is positioned on the rear substrate 104, and is covered by a protective layer 116. A fluorescent layer 118 used for producing fluorescent light is positioned on the address electrode 106.
The PDP 100 also has a plurality of pixel units 122, and each pixel unit 122 includes an address electrode 106, a sustain electrode 108, and a scan electrode 110. When the voltage across the sustain electrode 108 and the scan electrode 110 is larger than the firing voltage, the electric field between these two electrodes causes the gas to transform into spatial charges. Then, the spatial charges are transformed into plasma by applying a voltage across the address electrode 106 and the scan electrode 110, and whether the generated wall charges have a sufficient density or not to light the plasma is also determined. The wall charges density is the critical factor in maintaining the pixel units in the bright (on) state or in the dark (off) state. If it is decided not to maintain the pixel unit in the bright state, the spatial charges of the pixel unit are quickly restored to gas. If it is decided to maintain the pixel unit in the bright state, the sustain electrode 108 and the scan electrode 110 drive the plasma in the pixel unit back and forth for continuous radiating ultraviolet rays. When ultraviolet rays are radiated to the fluorescent layer 118, the fluorescence will gleam and the gleamed light emitted by the pixel unit will be seen by the user through the transparent rear substrate 104.
The sustain electrode 108 includes an opaque electrode 124 made by Cr/Cu/Cr or other high conductivity material, and a transparent electrode 126 composed of the ITO. Similarly, the scan electrode 110 includes an opaque electrode 128 composed of Cr/Cu/Cr or other high conductivity material, and a transparent electrode 130 made by the ITO. The material of Cr/Cu/Cr has the characteristics of high conductivity and not being pervious to light. The material of ITO, though being pervious to part of the visible light, has larger resistance and is difficult in manufacturing.
The firing voltage is proportional to the voltage across the sustain electrode 108 and the scan electrode 110, and corresponds to the gap between those two. Therefore, the transparent electrodes 126, 130 are respectively used as sustain electrode 108 and the scan electrode 110 in order to decrease the gap and the firing voltage as well. However, the transparent electrodes 126, 130 also consume larger energy owing to the large resistance and decrease the luminescence efficiency by absorbing part of the visible light. Furthermore, the difficulty in manufacturing for the transparent electrodes 126, 130 decreases the yield of the PDP 100.
It is therefore an object of the invention to provide a plasma display panel (PDP) has low firing voltage, high illuminating efficiency, and high contrast without using the transparent electrode.
The PDP of the present invention comprises a front substrate, a rear substrate, an addressing electrode, a common electrode, a first scan electrode, a second scan electrode, a first sustain electrode, and a second sustain electrode. The front substrate and a rear substrate are disposed apart in parallel, wherein a gas is filled there between. The addressing electrode positioned on the front substrate and the common electrode is positioned on the rear substrate and is orthogonal to the address electrode. The first scan electrode and the second scan electrode are positioned on the rear substrate, and are respectively at the first side and the second side of the common electrode. The first sustain electrode and the second sustain electrode are positioned on the rear substrate, and are respectively at the first side and the second side of the common electrode. A first pixel unit is defined by the address electrode, the common electrode, the first scan electrode, and the first sustain electrode. A second pixel unit is defined by the address electrode, the common electrode, the second scan electrode, and the second sustain electrode. A priming voltage is applied across the first scan electrode and the common electrode in an erasing period. Whether the first pixel unit is in bright status or not is determined by the address electrode and the first scan electrode in an addressing period. A plasma in the first pixel unit is driven by the first scan electrode, the first sustain electrode back and forth so as to sustain the bright status.